I think for 8.0 we're going to have to require MySQL 4.1. The change to the query to make it work actually defeats the purpose of the query
Basically we check to make sure no users belong to that group that do not belong to any other group (otherwise they end up orphaned). There's no simple way to do this without a subselect other than grabbing every user in that group and checking each individual one to see if they are not in another group. That would be very bad if the group had many users.
